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Free Online Calculators & Unit Converters

Instant, accurate tools for math, finance, health, and everyday decisions — percentage calculator, mortgage calculator, tax calculator, BMI, unit converters, and more. No sign-up. No ads.

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Most Popular

Percentage Calculator

Percent of, percent change, and reverse percentage.

Tip Calculator

Split the bill and calculate tip per person.

Discount Calculator

Find the sale price after any percentage discount.

Health Calculator

BMI, ideal body weight, and daily calorie needs in one place.

Compound Interest

Future value with contributions and compounding.

Mortgage Calculator

Monthly payment with taxes, insurance, PMI, HOA, and full amortization.

Geometry Calculator

Triangle area, perimeter, Pythagorean theorem, and circle calculations.

Statistics Calculator

Mean, median, mode, range, and standard deviation.

Tax Calculator

Estimate 2024 US federal income tax, effective rate, and take-home pay.

Car Loan Calculator

Monthly car payment with down payment, trade-in, and sales tax.

Graphing Calculator

Plot any math function — polynomials, trig, logs, and more.

Length Converter

Convert meters, km, miles, feet, inches and more.

Temperature Converter

Convert between Celsius, Fahrenheit, and Kelvin.

Volume Converter

Convert liters, gallons, cups, fluid ounces, and more.

Time Converter

Convert seconds, minutes, hours, days, weeks, and years.

Browse All Tools

Percentage CalculatorPopular
Percent of, percent change, and reverse percentage.
Open
Tip CalculatorPopular
Split the bill and calculate tip per person.
Open
Discount CalculatorPopular
Find the sale price after any percentage discount.
Open
GST / VAT Calculator
Add or remove tax from any amount instantly.
Open
Health CalculatorPopular
BMI, ideal body weight, and daily calorie needs in one place.
Open
Compound InterestPopular
Future value with contributions and compounding.
Open
Mortgage CalculatorPopular
Monthly payment with taxes, insurance, PMI, HOA, and full amortization.
Open
Loan EMI Calculator
Monthly payment with amortization summary.
Open
Scientific Calculator
Roots, powers, factorials, combinations, and logarithms.
Open
Fraction Calculator
Add, subtract, multiply, and divide fractions.
Open
Ratio Calculator
Simplify ratios and solve proportions.
Open
Geometry CalculatorPopular
Triangle area, perimeter, Pythagorean theorem, and circle calculations.
Open
Statistics CalculatorPopular
Mean, median, mode, range, and standard deviation.
Open
GPA Calculator
Calculate GPA from letter grades and credit hours.
Open
Tax CalculatorPopular
Estimate 2024 US federal income tax, effective rate, and take-home pay.
Open
Car Loan CalculatorPopular
Monthly car payment with down payment, trade-in, and sales tax.
Open
Graphing CalculatorPopular
Plot any math function — polynomials, trig, logs, and more.
Open
Length ConverterPopular
Convert meters, km, miles, feet, inches and more.
Open
Weight Converter
Convert kg, lb, oz, grams, and more.
Open
Temperature ConverterPopular
Convert between Celsius, Fahrenheit, and Kelvin.
Open
Speed Converter
Convert mph, km/h, m/s, knots and more.
Open
Area Converter
Convert square meters, feet, acres, hectares.
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Data Storage Converter
Convert bits, bytes, KB, MB, GB, and TB.
Open
Volume ConverterPopular
Convert liters, gallons, cups, fluid ounces, and more.
Open
Time ConverterPopular
Convert seconds, minutes, hours, days, weeks, and years.
Open
Pressure Converter
Convert Pa, bar, psi, atm, mmHg, and more.
Open
Energy Converter
Convert joules, calories, kWh, BTU, and more.
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Fuel Economy Converter
Convert mpg, L/100km, km/L and more.
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Date Difference
Find difference between two dates in days & weeks.
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Free Online Calculators & Converters

calctoolkit is a free collection of online calculators and unit converters for everyday math, finance, health, and science. Every tool runs entirely in your browser — results appear instantly with no loading, no sign-up, and no ads.

Our financial calculators cover mortgages, loans, compound interest, tax estimation, car payments, and GST/VAT. The health calculators include BMI, ideal body weight, and daily calorie needs. For students, the math tools handle percentages, fractions, ratios, statistics, geometry, and GPA.

The unit converters handle length, weight, temperature, speed, area, volume, pressure, energy, data storage, fuel economy, and time — covering both metric and imperial systems. Use the date difference calculator to find the number of days between any two dates.